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Transplantation. 2002 Dec 15;74(11):1486-9.

Tacrolimus pharmacogenetics: polymorphisms associated with expression of cytochrome p4503A5 and P-glycoprotein correlate with dose requirement.

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Division of Renal Medicine St. George's Hospital Medical School, London, United Kingdom.



There is marked heterogeneity in blood concentrations of tacrolimus following standard body-weight-based dosing. This is most apparent in black patients, who have a higher dose requirement when compared with other ethnic groups. Differences in intestinal P-glycoprotein and hepatic and intestinal cytochrome P4503A activity have been postulated as contributing to this problem.


The dose-normalized blood concentrations of tacrolimus at 3 months after renal transplantation were related to CYP3AP1 and multiple drug resistance (MDR)-1 genotypes determined by polymerase chain reaction followed by restriction fragment length polymorphism analysis.


We found that a single nucleotide polymorphism in the CYP3AP1 pseudogene (A/G(44)) that previously has been noted to be more common in African Americans and strongly associated with hepatic CYP3A5 activity correlated well with the tacrolimus dose requirement. A weaker association was found for a polymorphism in the MDR-1 gene, which influences intestinal P-glycoprotein expression.


The CYP3AP1 genotype is a major factor in determining the dose requirement for tacrolimus, and genotyping may be of value in planning patient-specific drug dosing.

[Indexed for MEDLINE]

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